Diffraction optics diffusing screen

Abstract

Optical apparatus (48) includes the holographic optical element (16) which diffracts the incoming ray (15) in a diffuse cone toward a viewing pupil and at an angle parallel to the axis of fiber optic faceplate (48) so the central ray (17) of the diffused cone passes through optical fiber (54) toward the viewing pupil. This permits the zero-order undiffracted light in ray (25) to be absorbed in the fiber optic faceplate (48).

What is claimed is: 
     
       1. An optical apparatus comprising: a holographic optical element possessing diffractive means therein by means of which a portion of a beam of light incident upon any particular point on said holographic optical element from a designated direction is diffusely diffracted toward a predetermined exit pupil so that light diffracted from said incident beam by said holographic optical element is substantially directed toward and illuminates said exit pupil with a selected intensity distribution; and   a fiber optic faceplate having light absorbing material and a plurality of substantially parallel optical fibers therein, said fibers positioned with respect to said holographic optical element so that said diffracted light propagates therethrough, the angle of diffracted light from said holographic optical element being sufficiently divergent from the incident light thereon that any undiffracted incident light impinging upon said fiber optic faceplate passes through said fibers and is absorbed in said light absorbing material.   
     
     
       2. The optical apparatus of claim 1 wherein said fiber optic faceplate causes scrambling of the diffracted light such that the illuminated cone from each fiber of said fiber optic faceplate has a total included angle of 2 theta where theta is the angle between the optical axis of said fiber optic faceplate and the farthest side of the incoming diffracted light cone into said fiber optic faceplate. 
     
     
       3. The optical apparatus of claim 2 wherein the incident light onto said holographic optical element is of more than one color so that the differently diffracted colors in the holographic optical element are substantially scrambled in said fiber optic faceplate to provide all colors substantially over the entire exit pupil. 
     
     
       4. An optical apparatus comprising: a holographic optical element having a surface and having diffractive means therein, said diffractive means receiving incoming light impinging on the surface of said holographic optical element and diffracting a portion of said light into a diffused bundle having a viewing pupil, said light having a central ray, said central ray in said diffracted light forming a different angle to said surface than said central ray in said incoming light; and   a fiber optic faceplate having a plurality of optical fibers therein, each being substantially parallel to each other and having said fibers directed substantially parallel to an axis, said fiber optic faceplate being oriented so that said axis thereof lies substantially parallel to said central ray in said diffracted light so that the diffused light bundle from said optical fibers of said fiber optic faceplate is directed at an exit pupil.   
     
     
       5. The optical apparatus of claim 5 wherein said fiber optic faceplate includes light absorbing material and said diffractive means in said holographic optical element diffracts light through a sufficient angle so that only the light diffracted by said holographic optical element is reflected within the optical fibers in said faceplate and thereby directed towards said exit pupil, whereas any incoming light which is not diffracted passes through the optical fibers at an angle less than the critical angle so that the undiffracted light is absorbed in said light absorbing material. 
     
     
       6. An optical system comprising: an information carrying screen;   a holographic optical element;   means for projecting light carrying information from said screen onto said holographic optical element, said projection means providing an incoming central ray from said information carrying screen to said holographic optical element;   diffraction means in said holographic optical element for diffusely diffracting a portion of the incoming light toward a viewing pupil; and   a fiber optic faceplate having light absorbing material and a plurality of substantially parallel optical fibers therein positioned between said holographic optical element and said viewing pupil, said fibers positioned so that diffracted light from said information screen propagates through said fibers and is viewable at said viewing pupil and light undiffracted by said holographic optical element passes through said fibers and is absorbed in said light absorbing material.   
     
     
       7. The optical system of claim 6 wherein said holographic optical element has a surface and said incoming central ray impinges upon said surface at a point at a predetermined angle and said optical fibers of said fiber optic faceplate are angularly directed away from said central ray at an angle greater than the critical angle.